Implant for bone connector

ABSTRACT

An implant for bone connector includes a fixing clamp, an implant body, a connecting portion and a movable clamp. The fixing clamp has a curved shape and supports a vertebral arch of a vertebra by grasping the vertebral arch. The implant body is provided on an upper portion of the fixing clamp. The connecting portion with which the connecting member is engaged is provided with the implant body. The movable clamp, which has a curved shape and grasps the vertebral arch, is provided to the implant body and is disposed to be opposed to the fixing clamp.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit of priority under 35 U.S.C. §119to Japanese Patent Application No.2001-233986, filed on Aug. 1, 2001,the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an implant for bone connectorused for connecting bones, and more particularly, to an implant for boneconnector having a connecting portion with which various connectingmembers are engaged.

[0004] 2. Description of the Related Art

[0005] When connecting bones such as thoracic vertebrae or lumbarvertebrae, the following method has been conventionally employed. Afirst implant 3 is screwed into centrum 1 such as the thoracic vertebraand the lumbar vertebra. A second implant 4 is screwed into centrum 2. Aconnecting rod 5 connects the first implant 3 to the second implant 4 asshown in FIG. 1.

[0006] The first implant 3 includes a screw portion and a head portion.The screw portion is screwed into centrum and the head portion with alarge diameter has a rod engaging groove. Also, the second implant 4includes the same conformation. Since end portions of the connecting rod5 are fixed to the rod engaging groove of the first implant 3 and thatof the second implant 4 respectively, the connecting rod 5 is integrallyfixed to the first implant 3 and the second implant 4 and accordingly abone connector is formed.

[0007] Further, an implant 9 is screwed into centrum 10 separating fromthe centrum 1 and the centrum 2 for hooking one end of a connectingmember 7 such as an artificial ligament. A hook portion 9F is providedon an upper portion of the implant 9, and one end portion of theconnecting member 7 is hooked over the hook portion 9F. Another endportion of the connecting member 7 is hooked over a hook portion 5Fprovided on one top end (the side engaged the first implant 3) of theconnection rod 5.

[0008] Also, instead of using the connecting rod 5, the connectingmember 7 may be used for connecting a first implant to a second implant.A first implant having a hook portion is screwed into the centrum 1, asecond implant having a hook portion is screwed into the centrum 2, andboth end portions of the connecting member 7 are hooked over the hookportion of the first implant and that of the second implantrespectively.

[0009] According to the above-described method screwing the implant forbone connector into the centrum for fixing a positional relation betweenvertebrae, it is necessary to precisely screw the implant into thecentrum without damaging other portion. This method requires hightechnique and a burden of the centrum becomes large, because the implantis screwed into centrum.

SUMMARY OF THE INVENTION

[0010] The present invention has been proposed in view of theabove-described circumstances, and it is an object of the presentinvention to provide an implant for bone connector capable of beingstably fixed to a vertebral arch of a vertebra without damaging thecentrum and to various connecting members.

[0011] In order to achieve the above object, the present inventionprovides an implant for bone connector comprising: a fixing clamp tosupport a vertebral arch of a vertebra by grasping the vertebral arch;an implant body provided on an upper portion of the fixing clamp; aconnecting portion provided to an upper portion of the implant body forengaging a connecting member which connects the implant with anotherimplant; and a movable clamp provided to the implant body and disposedto be opposed to the fixing clamp for grasping the vertebral arch.

[0012] According to the present invention, the fixing clamp is providedto a lower portion of the implant body, and supports the vertebral archof the vertebra by grasping the vertebral arch. The connecting portionis provided on the upper portion of the implant body, and the connectingmember is engaged with the connecting portion. The movable clamp isprovided to the implant body, is disposed to be opposed to the fixingclamp, and grasps the vertebral arch. Therefore, the implant can graspthe vertebral arch from both sides of the vertebral arch by means of thefixing clamp and the movable clamp, and is engaged with the connectingmember. As a result, it is possible to stably fix the implant to thevertebral arch without damaging the centrum, and the implant can be usedin the same manner as the conventional implant.

[0013] In a preferred embodiment of the present invention, the fixingclamp has a curved shape.

[0014] According to the embodiment, even if the fixing clamp has acurved shape, the fixing clamp can be engaged with the vertebral arch.Therefore, it is possible to stable fix the implant to the vertebralarch without damaging the centrum.

[0015] In a preferred embodiment of the present invention, the movableclamp can be moved and adjusted in a direction approaching the fixingclamp and separating from the fixing clamp.

[0016] According to the embodiment, since the movable clamp can be movedfreely in accordance with a size of the vertebral arch, the implant canstrongly grasp the vertebral arch from both sides of the vertebral archby means of the fixing clamp and the movable clamp, and be stably fixedto the vertebral arch.

[0017] In a preferred embodiment of the present invention, the movableclamp has a curved shape.

[0018] According to the embodiment, even if the movable clamp has acurved shape, the movable clamp can be engaged with the vertebral arch.Therefore, it is possible to stably fix the implant to the vertebralarch without damaging the centrum.

[0019] In a preferred embodiment of the present invention, theconnecting portion has a rod engaging groove, with a female threadportion, through which the connecting member passes, and has an engaginggroove, with a female thread portion, through which the movable clamppasses.

[0020] According to the embodiment, it is possible to fix the connectingmember and the movable clamp to the connecting portion by means ofdetent screws.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic diagram of a conventional implant for boneconnector;

[0022]FIGS. 2A and 2B are diagrams of an implant for bone connectoraccording to a first embodiment of the present invention;

[0023]FIGS. 3A and 3B are diagrams of an implant for bone connectoraccording to a second embodiment of the present invention;

[0024]FIG. 4 is a diagram of an implant for bone connector according toa third embodiment of the present invention;

[0025]FIG. 5 is a perspective diagram of the implant for bone connectoraccording to the third embodiment of the present invention;

[0026]FIG. 6 is an exploded perspective diagram of the implant for boneconnector according to the third embodiment of the present invention;and

[0027]FIG. 7 is a diagram showing one using example of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Three embodiments of an implant for bone connector according tothe present invention will be explained in detail based on the drawings.Constituent elements having the same functions as those of theabove-described conventional configuration are designated with the samesymbols, and redundant explanation is omitted.

[0029]FIGS. 2A and 2B show a first embodiment of the present invention.As shown in FIG. 2A, an implant 11 includes a block-like implant body13, an U-shaped curved fixing clamp 15, and a movable clamp 17. Theimplant body 13 has a circular or rectangular cross section and has aconnecting portion which is engaged with a connecting member such asconnecting rod 5. The fixing clamp 15 is integrally provided to a lowerportion of the implant body 13 for supporting a vertebral arch 3A of avertebra by grasping the vertebral arch 3A. The movable clamp 17 isprovided to a lower portion of the implant body 13 for grasping thevertebral arch 3A of the vertebra, and is disposed to be opposed to thefixing clamp 15.

[0030] More specific configuration of the lower portion of the implantbody is as follows. The movable clamp 17 includes a movable rod-likeclamp body 17B and a curved hook potion 17F. As shown FIG. 2B, themovable clamp body 17B is fixed into an engaging groove 19 formed withinthe implant body 13 by means of a detent screw 25. The hook portion 17Fis provided to be opposed to the fixing clamp 15 on a tip end of theclamp body 17B. The hook portion 17F grasps the vertebral arch 3A.

[0031] A position of the movable clamp 17 is adjusted in a directionapproaching the fixing clamp 15 and separating from that for graspingthe vertebral arch 3A. Also, it is possible to rotate and adjust themovable clamp 17 around an axis of the rod-like clamp body 17B. In orderto fix the movable clamp 17 in the position fitting to a size of thevertebral arch 3A, a female thread portion 23 is formed on a surface ofthe engaging groove 19. Therefore, the movable clamp 17 is fixed in aproper position by screwing the detent screw 25 into the female threadportion 23. As a result, it is possible to adjust the movable clamp 17to the desired position.

[0032] A rod engaging groove 27 to be fixed to the connection rod 5 isformed at an upper portion of the engaging groove 19. A width of the rodengaging groove 27 is slightly greater than that of the engaging groove19. A female thread portion 29 is formed on a surface of the rodengaging groove 27. A detent screw 31 for fixing the connection rod 5 tothe implant body 13 is screwed into the female thread portion 29.

[0033] With the above configuration, the fixing clamp 15 supports thevertebral arch 3A by grasping the vertebral arch 3A, and the hookportion 17F of the movable clamp 17 grasps the vertebral arch 3A.Therefore, the implant 11 can grasp the vertebral arch 3A from bothsides of the vertebral arch 3A by means of the fixing clamp 15 and themovable clamp 17. Thereby it is possible to stably fix implant 11 to thevertebral arch 3A without damaging the centrum. At that time, it is easyto fix the implant 11 to the vertebral arch 3A, because the detent screw25 can be rotated and operated without interruption of vertebra andanother implant by means of a tool for screwing the detent screw 25 intothe female thread portion 23 from the upper direction of the femalethread portion 23.

[0034] As described above, after the implant 11 is fixed to thevertebral arch 3A in this manner, the connection rod 5 is fixed to therod engaging groove 27 by screwing the detent screw 31 into the femalethread portion 29, thereby the connection rod 5 is fixed to the implant11.

[0035] In the above-explained embodiment, the movable clamp 17 and theconnection rod 5 are fixed to the implant body 13, and the engaginggroove 19 and the rod engaging groove 27 are formed in the implant body13 such as to open upward. Alternatively, holes through which themovable clamp 17 and the connection rod 5 pass may be formedhorizontally, and accordingly female thread portions into which thedetent screws 25 and 31 are screwed may be formed to each upper potionof the former hole.

[0036] It is also possible to form a male thread in an outer peripheralsurface of the implant body 13, and to screw a nut member into the malethread for fixing the movable clamp 17 and the connecting rod 5 toimplant body 13. At that time, using the clamp body 17B of the movableclamp 17, it is also possible to provide a long hole in the clamp body17B through which the implant body 13 can pass such as to sandwich theimplant body 13, and it is also possible to make the clamp body 17B as abifurcated configuration.

[0037]FIGS. 3A and 3B show a second embodiment of the present invention.In this embodiment, an annular recess 13C is formed on a connectingportion with which a connecting member 7 is engaged, and the connectingmember 7 such as artificial ligament, wire or cable instead of theconnection rod 5 may be used. Other configuration is the same as that ofthe previous embodiment, constituent elements having the same functionsare designated with the same symbols, and redundant explanation isomitted.

[0038] FIGS. 4 to 6 show a third embodiment of the present invention. Inan implant 11 of this embodiment, a movable clamp 33, which is disposedto be opposed to the fixing clamp 15 and which grasps the vertebral arch3A, is provided on an upper portion of the implant body 35. The movableclamp 33 can be freely slid and turned or fixed.

[0039] More specifically, as shown in FIG. 6, a thread hole 35H isformed on an upper surface of the implant body 35 having the fixingclamp 15, and a thread portion 37S which is screwed into the thread hole35H is provided on a lower portion of the hook portion 37. The movableclamp 33 includes a curved hook portion 33F on a tip end of a clamp body33B. The clamp body 33B of the movable clamp 33 has a slit or a longhole 33H. Since the movable clamp 33 is disposed to be opposed to thefixing clamp 15, the hook portion 33F grasps the vertebral arch 3A ofthe vertebral arch at the opposite side of the fixing clamp 15.

[0040] In the above configuration, as shown in FIG. 6, the clamp body33B of the movable clamp 33 is disposed between the implant body 35 andthe hook portion 37 and then, the thread portion 37S of the hook portion37 is allowed to pass through the long hole 33H formed in the clamp body33B and to be screwed into the thread hole 35H of the implant body 35.Then, the movable clamp 33 is sandwiched between the implant body 35 andthe hook portion 37.

[0041] In a state in which the movable clamp 33 is softly sandwichedbetween the implant body 35 and the hook portion 37, the movable clamp33 can be moved and adjusted in a direction approaching the fixing clamp15 and separating from that, and the movable clamp 33 can be rotated andadjusted around the thread portion 37S of the hook portion 37.Therefore, the movable clamp 33 can be adjusted to a size of thevertebral arch 3A. If the thread portion 37S of the hook portion 37 isstrongly fastened to the thread hole 35H, the clamp body 33B of themovable clamp 33 is strongly sandwiched and fixed between the implantbody 35 and a lower flange 37F provided on a lower portion of the hookportion 37. Therefore, the implant 11 can firmly grasp the vertebralarch 3A from both sides of the vertebral arch 3A by means of the fixingclamp 15 and the movable clamp 33. That is, in this embodiment, the hookportion 37 serves as a hook over which the connecting member 17 ishooked, and as a fixing tool for fixing the movable clamp 33.

[0042] Since the implant 11 firmly grasps the vertebral arch 3A fromboth of sides of the vertebral arch 3A by means of the fixing clamp 15and the movable clamp 33, the implant 11 can be fixed to the centrum.Therefore, the same effect as the implant 11 of the first and the secondembodiments can be obtained, and the implant 11 can be fixed to thecentrum more stably.

[0043]FIG. 7 shows one example in which the connecting member 7 ishooked over the implant 11 and the implant 9. In this case, the implant9 which is screwed into centrum is used instead of the implant 11.

[0044] The above-described embodiment is one example of the presentinvention. Thus, the present invention is not limited to the aboveembodiment, and various modifications can be made in accordance withconfiguration within a range not departing from technical idea of theinvention.

[0045] That is, although both the fixing clamp and moving clamp havecurved shapes respectively in the three embodiments, the presentinvention is not limited to this, and the invention can be applied onlyif the vertebral arch 3A of the vertebra can be grasped.

What is claimed is:
 1. An implant for bone connector comprising: afixing clamp to support a vertebral arch of a vertebra by grasping thevertebral arch; an implant body provided on an upper portion of thefixing clamp; a connecting portion provided to an upper portion of theimplant body for engaging a connecting member which connects the implantwith another implant; and a movable clamp provided to the implant bodyand disposed to be opposed to the fixing clamp for grasping thevertebral arch.
 2. An implant for bone connector according to claim 1,wherein the fixing clamp has a curved shape.
 3. An implant for boneconnector according to claim 1, wherein the movable clamp can be movedand adjusted in a direction approaching the fixing clamp and separatingfrom the fixing clamp.
 4. An implant for bone connector according toclaim 3, wherein the movable clamp has a curved shape.
 5. An implant forbone connector according to claim 1, wherein the connecting portion hasa rod engaging groove, with a female thread portion, through which theconnecting member passes, and has an engaging groove, with a femalethread portion, through which the movable clamp passes.